ASML is filing initial legal claims against Nikon for infringement of more than 10 patents, related to a broad range of products in the fields of semiconductor manufacturing equipment, flat panel display manufacturing equipment and digital cameras.

This follows Nikon's previous announcement that it had sued ASML. ASML denies infringing any of Nikon's patents.

ASML has today filed suits in Japan, both on its own and jointly with its strategic partner ZEISS. Additional suits will be brought in the United States.

Peter Wennink, ASML President and Chief Executive Officer, said: "We have no choice but to file these countersuits. We have tried for many years to come to a cross-license agreement that reflects the increased strength of our patent portfolio. Unfortunately, Nikon has never seriously participated in negotiations. Now that Nikon has decided to take this dispute to court, we also have to enforce our patent portfolio, and we will do this as broadly as possible."

Nikon claims that ASML has infridged its own patents. In 2001, Nikon went to the United States International Trade Commission (US ITC). Two years later, the Commission found no violation and ASML won on all 15 accounts. ASML and Nikon subsequently settled in a cross-license agreement that allowed both companies to focus on further developing products and serving chipmakers, without the distraction of an intellectual property dispute. Some patents were perpetually licensed; for others, the license period ended on 31 December 2009. A transitional period, during which the parties had agreed not to bring suit, ended on 31 December 2014.

Over the last decade, ASML has built up a strong portfolio of more than 10,000 patent rights. The application of these innovations has been adopted by all of the world's largest chipmakers.